With the primary season underway, America is focused on whether the next president will be Democrat or Republican. Meanwhile, within the Democratic Party another struggle is unfolding. NOW on PBS reports on a rift between progressives who believe the party has sold out its liberal values and centrists eager to capture a broad swath of the more conservative voters. It's a struggle that is taking place at all levels of government.

In Maryland, eight-term incumbent Al Wynn is facing a tough challenge from newcomer Donna Edwards. According to Edwards, Wynn has sold out to big business and the Bush agenda, including a vote for the war in Iraq and the 2005 energy bill. Wynn says his challenger is naïve and doesn't understand that there are choices in politics between compromise and doing nothing. Fueling candidates like Edwards are the foot soldiers of the progressive battle—bloggers and other political outsiders like Matt Stoller of OpenLeft.com who are drumming up national support on the Internet. Maria Hinojosa speaks with the candidates and Matt Bai, author of The Argument: Billionaires, Bloggers, and the Battle To Remake Democratic Politics.

Also This Week: The Captain and Climate Change: An Interview with Captain Dan Kipnis

David Brancaccio talks to Captain Dan Kipnis, an award-winning sport fisherman and conservationist. Captain Kipnis sits on the Miami-Dade County Climate Change Task Force, and also speaks to commercial fishermen and other groups about what climate change could to do to their environment. David and Dan discuss where the environment stands in voters' minds and on the campaign trail. Kipnis says that if drastic measures aren't taken in the immediate future, Miami-Dade County could be under water in 20 years.